Electrolytic cell



June 6, 1939. R. M. HUNTER ELECTROLYTIC CELL Filed May z, 1937 5 Sheets-Sheet 2 r. Rzm.w 0 E M MM fm m6 r M/ A E. 6 /fi June 6, 1939. R. M. HUNTER 2316],166l

ELECTROLYTIC CELL 3 Sheets-Sheet 3 Filed May 3, 1937 MYM Patented June 6, 1939 ELECTROLYTIC CELL Ralph M. Hunter, Midland, Mieli., assignor .to The Dow Chemical Company, Midland, Mich., a corporation of Michigan Application May 8, 1987, serial No. 140,291

. 1 Claim.

The present invention is concerned with electrolytic cells for the electrolysis of aqueous saline solutions to produce halogen, hydrogen and alkali, and relates specifically to cells for the electrolysis of an aqueous sodium chloride solution for the production of chlorine gas, a caustic soda solution, and hydrogen gas.

My invention comprises novel unit cells adapted to assembly into a battery of cells of the socalled filter press type, and a so-assembled battery thereof. It is specifically concerned with the electrolysis of an aqueous sodium chloride solution for production of chlorine, hydrogen and caustic soda-salt solution, the cells in each battery in parallel electrically.

The object of my invention is to produce a type of apparatus capable of easy and economical fabricatiomconstructible in large sizes to carry heavy currents,-requiring a minimum floor space per kilowatt capacity,--accessible for necessary Operations incident to use, repair and replacements,-having a long active life, a high efficiency and producing high strength chlorine gas.

Theseobjects I have accomplished by employing anode and cathode cells of plate form, arranged in alternating sequence and clamped together as in the filter press type arrangement. I arrange the cells with active anodic or cathodic faces on both sides for operation in parallel.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the means hereinafter fully described and particularly pointed out in the claim, the annexed drawings and the following description setting forth in detail certain means for c'arrying out the invention, such -disclosedfineans illustrating, however,'but one of the various ways in which the principle of the invention may be used.

In the annexed drawings, Fig. 1 is a top plan view of a cathode-cell unit. Flg. 2 is a vertlcal elevation or face view of such a unit. Fig. 3 is a Vertical cross-section taken on the line 3--3A of Fig. 2. Fig. 4 is an elevation of the right hand end of the cell unit of Flg. 2, and Flg. 5 is an elevation of the other end thereof.

Fig. 6 is a top plan view of an anode-cell unit. Fig. 7 is a side elevation'or faceview of the unit shown in Flg. 6. Flg. 8 is a Vertical crosssection of the 'unit taken on the line 8-8 of Fig. '7. Fig. 9 is an elevation of the left hand end of Flg. 7. Fig. 10 is an elevation of the other end thereof.

Fig. 11 is a top plan view of an assembly of cell units comprising two cathode cells 1 and one anode cell 2. Fig'. 12 is a Vertical cross-section of the assembly of cells taken on the line |2-12of Fig. ll, in which the cell 2 is an anode cell and the cells I are cathode cells.

Referring to Figs. 1 to 5, inclusive, showing plan, elevations, and section of a cathode cell; the cell comprises a rectangular concrete frame I, cast about an inner rectangular steel channel frame 4, the latter having a horizontal width preferably slightly lessthan that of the concrete portion. A lug 5 of copper is attached to the channel frame 4,- extends through the concrete frame to the outside thereof, and serves to lead away current collected by the frame and its members. Within frame 4 and extending horizontally therein are two steel perforated bars 6 of substantially the same width as the channel 4, which bars are attached electrically to the channel frame 4 and serve as additional collectors of current. Cathode screens 8, two in Inumber, are applied to and attached electrically to the faces of the frame 4 and to the edges of bars 6. Only a portion of such a cathode screen is shown in Fig. 2. To the outer face of each cathode screen 8 is applied a diaphragm 9 of suitable character, only a portion thereof being shown. The so-assembled frame constitutes a cathode cell electrically active upon both diaphragmed faces, which faces enclose between them a chamber 10. Chamber 10 is drained through a serpentine trap 12, cored in the concrete. which trap 'is open at 12a and |2b, but is plugged at |2c and |2d. Upon the upper horlzontal member of the cathode cell frame are cast two lugs 13 and an eye 14, having an inlet 14a extending from the chamber 10 into the eye hole l4b, and an access hole |4c through the wall top of 14 opposite 14a. Iron lugs 15 are' connected rigidly to the channel 4 and project beyond the concrete, affording grips for hoisting and handling of the unit cath- -ode cell just descrlbed in detail.

Referrlng to .Figs. 6 to 10, inclusive, illustrating an anode cell; this cell comprises a rectangular concrete frame 16 having lugs 13a corresponding to those shown in Flg. 2, and an eye |4d corresponding to eye 14 vof the cathode-cell shown lin Fig. 2. This frame is also provided with lugs' 15 similar to' those shown in Fig. 2 for a like purpose. The eye |4d is open only at the ends. Piercing the upper member of the lframe are two openings 11 communicating with the interior compartment IGaof thecell. Suitable anodes 18, here shown as rectangularlslabs of graphitized carbon, are attached by means of graphite lscrews. 18a. to a series of four graphitizcd` anode carrier bars 19, which pierce one' end of the-frame 'and extend outwardly thereof, having fiattened faces for the attachment of current supply leads. The other ends of the bars |9 are socketed in the opposite end of the anode frame. The active anodes |8 will be seen to practically cover in assembly the two faces of the anode cell presenting active faces towards the faces of the cell unit. Each individual anode is supplied with current from the transverse carrier bar |9 to which it is connected. A hole |6b at a lower corner of the compartment |6a serves for drainage when desired, but is plugged when the cell is operating.

Referring now to Figs. 11 and 12, showing an assembly of cells, it will be seen that the unit cells are assembled in a Vertical position, face to face, in alternating sequence, that the terminals of the anode bars |9 projectat one side of the assembly, and .the cathode lugs 5 at the other side thereof. When the anode compartment is filled with electrolyte, e. g., an aqueous solution of 'NaCL introduced through the openings I? and held therein by the diaphragms which have been applied to the cathode screens 8 before assembly of the cells in battery, electric current supplied to the .terminal' of bars |9 will pass to the active anodes |8, thence through the electrolyte and the diaphragm to the cathode screens 8, from which it will be collected by the bars 6 and the channel frames 4 and be led away at the terminal lugs 5. Chlorine gas generated by the passage of the electric current will rise through the electrolyte, collect in the upper portion of the compartment |6a., and escape through openings Il to a conduit 20, which will be described hereinaften' To the conduit 20 is supplied fresh electrolyte in quantity and at a rate to maintain the compartment la filled therep with.

That portion of the electrolyte which percolates through the diaphragms trickles down the cathode screens 8 as an alkali salt solutionbf NaCl and NaOH, being collected in compartment lt, from which it escapes by way of the trap IZ. The hydrogen gas liberated upon the cathode screens escapes into compartment IO, from which it issued via duct Ma. into conduit Mb, from which it may be removed at either end thereof or from an appropriate outlet therefrom.

The illustrated assembly of three cells in Figs. 11 and 12 constitute a portion of a larger number of cells in battery, the number being chosen to suit Operating conditions. But three are illustrated for simplicity. A larger battery may contain 2 or more anode-cell units I and a corresponding number plus one of cathode-cell units 2 After assembly of the cathodeand anode-cells in alternating sequence to form a battery, an inverted trough-like conduit member 20, which may be of concrete fabricated in Sections of con-- venient length, which length may approximate the width of a plurality of cell frames, is applied to the assembly as shown and is luted thereto by suitable luting material 42|. Suitable luting material vis also applied to 'thejoints between the adjacent sections of conduit 20 and suitable closures are applied to the ends of the so-construct-- ed conduit. Openings, e. g., such as shown at 22, will be provided for access-to passages H.

In the assembly of the lcells into a battery, the joining faces may be sealed as by a luting' material applied to the portons of the cathode-cell frame faces contacting with the anode-cell frame faces to seal the joints when the cells are clamped together into an assembled battery.

each active anode surface, and the anode compartments lGa, are formed.

The assembled structure may be supported in any convenient manner, as by skids or sleepers, indicated at 24 in Fig. 7, upon which the lower transverse members of the cell frames rest in slidable relation thereto. A suitable drain trough or conduit (not shown) may be provided to receive the efiluent from the traps |2, and likewise suitable offtakes will be applied to the conduits Mb and 20 for taking away respectively the hydrogen and chlorine gases. Suitable inlet and supply means for electrolyte will be provided to conduit 20 to maintain the feed of electrolyte to the cell battery.

The anode termlnals 19 of the anode-cells in each assembled battery will be connected in parallel with a source of electric current, and similarly the lugs 5 of the cathode-cell units will be connected in parallel to an electrical conductor to lead away the current from the battery. The cells in each such assembly will operate in parallel electrically.

As illustrated and described in detail, the cathodeand anode-cell units and an assembly thereof in a battery are suited to the electrolysis of a solution of sodium chloride for the production of chlorine, cau'stic soda, and hydrogen. Such apparatus is suited in general to the electrolysis of aqueous alkali halide solutions, e. g., for the' electrolysis of a| KCI solution.

For such purposes, asbestos paper diaphragms may be used. Cathodes'may be of steel Wire cloth or perforated sheet steel welded to the channel frame and bars. The anodes may be of graphitized carbon as may also the anode carrier `bars and terminals IS. The concrete will be preferably high in silica, relatively free from lime, and may be treated, as by impregnation, to make it less susceptible to attack by chlorine or chlorine' water. The luting material between the cell frames may comprise ground asbestic, water, and an inert material such as Portland cement or clay. A rope gasket may also be applied to the faces of the anode cells along the faces of the frames thereof to contact with and be pressed into the plastic lute applied to the faces of the cathode frames. The luting material used in applying the conduit 20 may be chlorine putty or other suitable plastic luting cement resistant to chlorine. The buckstays may be of concrete, Wood. steel or other suitable material, and the tie-bolts may be of steel.

Instead of constructing conduit 20 as described, I may provide eyes in all cell frames which will coact to form a gas conduit as illustrated in con-,

i tail` forms of cells in which concrete, steel., and

`may be substituted. Concrete may e. g., by constructing the and thel anodecells of rub- 2,101,186 I graphitized carbon are used, it will be'obvious delivery pipeas great as desired according to to one'skilled in the art that other materials -the number of cells in one battery. The floor be dlspensed with in part or entirety, cathode cells of steel ber-iined steel, or o f steel otherwise protected. Any chiorine resistant, electrically non-conductive structural material, e. resinous compositions, may be-employed for the frames. suitable gaskets may be'used between consecutive metal cell frames to electrically insulate them one from the other and to 'seal the joints. -ne only anode bar, or a plurality of such, or their equivalent may be used as suits availability of material and size of the unit. 0ther materials than graphitized carbon may be used, e. g., magnetic oxide of iron, orfmetals resistant to electrolytic chlorine. But in any case,

the total frame areas, needed for the margins ot .the frames. The cells the individual cells will be of flat form, preferably rectangular, each presenting two active' cathode or 'anode surfaces'to diaphragms clamped between alternating cathodeand anode-cell units,

.having terminal leads .extending outside1 of the.

cells either through side, bers of the frames as may be be assembled into batteries of convenient number, the cells in any one battery operated in parallel, and successive .batteries in series to accommodate the voltage available;

top or bottomv memcathodes may be of metal .wire cloth or perforated sheet metal.

I have found cells described herein easy and economical of fabrication. I. have built and used such cells in' large sizes to take individually' 2000 amperes of direct current-` Buch batterie may be 'assembled to permitoperation with `any prac- 'ticable currentinput. 'areas are'large and cover large' percentages of The. anode' and cathode leaving' but little space and assembled into batteries, feed battery and but one each gasv perbattery.. thereby d economical. They are also'easiiy dis-assembled for repair and-replacement. Their life is current emciency is very high. The causti muent is of normal ccncentration, and gas delivered il lof high str'ength and. in. quantity per.

are easily handled g., synthetic resins or desired, and will satisfactory and the single' degree.

.Other modes Of applying the principle of my low per .kilowatt input, as low as may be secured with any type of cell' and By choosbattery and the invention 'may he employed .instead of the one explained, change being made as regards the mechanism herein disclosed, provided the -means stated by the'following claim or the equivalent of such stated means be employed.'

I, therefore, particularly point out and distinctly claim as my invention'.

In an electrolytic apparatus of the filter press type for producing chlorine and caustic soda, the combination lof a plurality. of alternating vertically disposed anode and cathode cell units clamped together; said anode units comprising a rectangular frame of non-conducting material, transverse anode carrier bars of graphitized carbon within said frame .and projecting there-- through at one end to form an electrical terminal, flat graphitized carbonblocks" attached to each carrier bar and facing laterally outward on either side thereof so as to cover largely the lateral area by said frame, the o uter faces of 'said blocks forming the active anode surfaces,. Outlet and a 'gas and said cathode an inlet for cell. feed, liquor through the top of said frame;

'unit comprising a rctangular frame of non-conducting material cooperating with the frame of the adjacent anode units' and having on each lateral face 'a perforated metal plate or screen overlaid with a to said plateor screen and at the bottom an outlet for cell liquor; common porous diaphragm, an electricalv terminal attached electrical connections' to the termin'ais .of said anode unit/s and of said cathode units, 'respectively, a common header communicating with the openings in the top of said anode units for feedin'g cell liquor thereto and for .removing gas, and

a common headercornmunicating with the top of said cathode units for removing gas;

v BALPH M. 

